1. Field of the Invention
The invention relates generally to techniques of optically displaying an image, and more particularly to improvements in techniques of adjusting a wavefront curvature of imaging light representing an image to be displayed.
2. Description of the Related Art
As techniques of optically displaying an image, there are known, for example, a technique of projecting imaging light representing an image to be displayed, directly onto a viewer's retina, to thereby allow the viewer to perceive the image as a virtual image, and a technique of projecting such imaging light onto a physical display screen, to thereby allow the viewer to perceive the image as a real image.
Further, as techniques of converting light emitted from a light source into imaging light representing an image to be displayed, there are known, for example, a technique of spatially modulating surface light emitted from a light source at a time, using a spatial light modulator such as an LCD (Liquid-Crystal Display), on a per-pixel basis, to thereby generate the imaging light in the form of surface light, and a technique of two-dimensionally scanning an intensity-modulated light beam emitted from a light source, using a scanner, to thereby convert the light beam into the imaging light in the form of surface light.
Japan Patent Application Publication No. hei 9-297282 discloses a head-mounted display device acting as an exemplary device for optically displaying an image. This head-mounted display device employs a technique of projecting imaging light representing an image to be displayed, directly onto a viewer's retina, to thereby allow the viewer to perceive the image as a virtual image, and a technique of spatially modulating surface light emitted from a light source at a time, using a spatial light modulator such as an LCD (Liquid-Crystal Display), on a per-pixel basis.
The disclosed head-mounted display device further employs a variable-focus lens for varying the position of a virtual image in a depth direction, for three-dimensional representation of a moving picture.